A cracked spinner fairing that caused the failure of a Gulfstream IV Rolls-Royce Tay engine resulted in revised inspection procedures that could help detect such cracks before they cause damage. The event took place on June 17, 2023, and the final NTSB report cited as a contributing cause “inadequate spinner fairing inspection procedures that did not require removal of the spinner fairing to inspect the aft side for earlier detection of crack indications.”
The incident took place during a charter flight operated by Planet 9 Private Air as the crew began a step climb at FL400. After the right engine failed, the pilots diverted to Sioux Gateway Airport in Sioux City, Iowa, and made a successful single-engine landing. No one was injured.
Inspection of the Tay 611-8 engine’s spinner fairing is required every 2,000 hours for corporate operations and 600 cycles for regional operations. In this case, the 2,000-hour interval applied, and the spinner fairing was inspected on Oct. 12, 2022, and had accumulated 542.2 hours since. According to the maintenance manual procedure, technicians were tasked with inspecting “for cracks and indentations emanating from spinner fairing bolt holes.” However, according to the NTSB, “The procedure did not call for removal of the spinner fairing from the nose cone."
After the spinner fairing separated from the engine, it impacted the leading edges of the fan blades and the inner barrel of the fan case and caused one fan blade to fracture. According to the NTSB report, “The subsequent fan imbalance resulted in severe vibrations that caused an anti-ice air line b-nut connector to back off, the P3 limiter to separate from the fuel flow regulator at the mating flange, and a fuel line fracture at the acceleration reset solenoid. The fuel line fracture at the acceleration reset solenoid resulted in a fuel leak that persisted until the airplane landed. There was no evidence of undercowl fire or thermal damage on the engine or nacelle.” The inlet cowl’s acoustic honeycomb liner had multiple impact gouges and a penetration measuring about 12 inches in circumference.
“The origin of all Rolls-Royce Tay model spinner fairing crack findings to date has been the heat-affected zone of the tack welds that secure spacers to the aft side of the fairing, and therefore, early crack detection would have only been possible if the spinner fairing was removed to inspect the aft side.”
On Oct. 20, 2023, Rolls-Royce issued updated nose-cone fairing inspection criteria, the NTSB report noted, “to add an instruction to remove the spinner fairing to allow for inspection of the aft side. The [Notice To Operators] states, ‘This facilitates earlier detection of cracks by allowing inspection of the welds, where cracks are known to initiate.’ A requirement was also added to inspect whenever the fairing is removed from the engine.”
In addition, Rolls-Royce has redesigned the spinner fairing with a bonded spacer. Once a manufacturer for the new design is identified, according to the NTSB report, “it will be incorporated through attrition rather than as a mandatory replacement campaign.”